get a hydration pack or a bladder bag to fit in a back pack to carry water, very convenient. Another cool helpul thing to have are katadyn micropur mp1 water tablets, they purify filthy water and used by the military.

Water bladder, and pack that fits them. A good walking stick will save your knees going down hill and save you from many would be falls. If you are going very far, a small survival kit with fire starter, water filter, emergency blanket, flashlight, knife, first aid kit. A good gps with topo maps can be a real plus for picking your way cross country.

Get the Boy Scout handbook and look in the index for the 10 Essentials of Hiking. Get all those items and carry them in a day pack when you go out. Also read up on the Rule for Safe Hiking, and if you're over 40, make sure you are in shape before you venture off alone. Unless you're backpacking, just get a pair of good low-cut hiking shoes -- tennies with a stiffer midsole and aggressive tread. For areas of sand, gravel and stuff, add some low gaiters. For areas of wet, make sure you get goretex liners in the shoes. My recommendation: if you are new to all this, go to a backpacking store and get someone to help you and don't get anything at Walmart until you know enough to pick out the garbage from the good stuff.